KEKS Pay

• New Payment page setting. When set (e.g. checkout/keks-pay?number={number}), "Pay" sends the customer to that site page instead of straight into the app, so desktop customers get a QR code to scan. Empty keeps the old redirect into the app.
• craft.keks.payment(order) returns the QR code, the app link and the poll URL, for a payment page that renders its own markup.
• The payment poll looks orders up by number instead of id. Ids are sequential, and a paid order's poll answer leads to its confirmation page.
• The poll reports a failed payment (failed: true and the order's cancel URL) instead of waiting forever.
• The app's success and fail URLs are absolute. Commerce stores the order's return URL relative to the site, which the app could not open.

• getPaymentFormHtml() returns nothing when no order is passed, instead of a Twig error. A checkout that renders every gateway's form before payment (getPaymentFormHtml({})) no longer fails with a 500.

First public release, after two years installed on Croatian stores.

• QR code and app deep link on the checkout, GET redirect into the KEKS Pay app from the Commerce payment form.
• Bank callback at keks-pay/keks/processing and at Commerce's webhook URL: token check, amount matched to the order, idempotent for repeated callbacks.
• Checkout page polls the order every five seconds and moves on once it is paid.
• Refund from the order's Transactions tab with the 3DES request hash.
• Settings accept environment variables; Croatian translations for the control panel and the checkout strings.